Sure all of these things could happen. But they aren't as scary as what is actually happening, right now, in Africa.

The ebola outbreak continues to get worse. And it may only be a matter of time before it reaches North America. A scary take can be found in this new york times piece.

"There are two possible future chapters to this story that should keep us up at night.

The first possibility is that the Ebola virus spreads from West Africa to megacities in other regions of the developing world. This outbreak is very different from the 19 that have occurred in Africa over the past 40 years. It is much easier to control Ebola infections in isolated villages. But there has been a 300 percent increase in Africa’s population over the last four decades, much of it in large city slums...

The second possibility is one that virologists are loath to discuss openly but are definitely considering in private: that an Ebola virus could mutate to become transmissible through the air."
(new york times)